Changing the leader can be one of the most difficult things a political party can do in a democracy, as the National party is perhaps about to find out.

The process they may be about to embark upon could well be fraught with difficulties; it seems unlikely that they will find it as straightforward as Labour did last year.

To be fair, the luck very much ran Labour’s way last year. An accommodating, not to say selfless, leader in Andrew Little, reached his own conclusion that it was time to go. The Labour party had already identified, in Jacinda Ardern, a deputy leader who could succeed to the leadership with a minimum of angst. As it turned out, she was able to resolve one of the most difficult potential conflicts faced by political parties – how to choose a leader who will command the support and loyalty of party activists as “one of us”, while at the same time appealing to the wider electorate. All too often, a potential leader will commend himself or herself to the party faithful but will be a complete turn-off for the non-political public.

It was Labour’s good fortune that their leader-in –waiting was not only the obvious and widely supported candidate from within the party, but that she immediately proved her vote-winning credentials.

National, on the other hand, has a more difficult row to hoe. Bill English is a widely respected leader, still enjoying support from his party and under no immediate pressure to go. While National has a deputy leader, there is no widely accepted successor, as we are about to find out. And because that is so, the field is open to other challengers, though each will have counts against him or her. None has quite the same freshness and novelty value that Jacinda Ardern enjoyed when she first emerged into the limelight.

National’s contenders will, in other words, bring a certain amount of baggage with them into a leadership contest. And, in an open democracy such as ours, any question marks from their past will be remembered and refreshed in the public memory. Whether it be a disastrous television interview or pulling a fast one as a Minister, the contenders will have to disabuse boththe public and their party’s supporters of those unfortunate memories. Sadly for them, the likely candidates all seem to be handicapped by past indiscretions or failures – they will have to hope that their supporters are a forgiving lot.

In modern politics, it will almost certainly be the case that a good deal of what is known as “qualitative polling” will be carried out, to find out just how the contenders are seen by the public, when asked their opinions in what are known as “focus groups”. I remember that when I ran the 1987 election campaign in the UK for the British Labour Party we did this kind of polling, about policies as well as personalities. It came as quite a shock to us to discover that one of our leading spokespeople was a complete “no-no” for the public.

And, for the purposes of a poll among party members, and even more among MPs, a demonstrated capacity to alienate undecided voters on the part of a candidate will ring the deal knell for that candidate’s hopes. Responding to a television interviewer rudely and aggresssively may appeal to the party, as supposedly demonstrating leadership qualities, but it will be seen as off-putting by the non-committed. As the contenders line up, they will be hoping that memories are not too long and that they can start with a clean slate.

There is one further hurdle for them to surmount. The shoe is now well and truly on the other foot. Labour had to endure years of John Key’s unusual ability to appeal to the voters. Now, National have the extra burden of choosing someone who can contest toe-to-toe with Jacinda Ardern. And the contest is not just about policies, important though they are – it is about the whole package, principle, personality, the lot.

Being as objective as I can, I cannot, when I survey the field of National hopefuls, see anyone who fills the bill from among the supposed frontrunners. Trying someone who is completely untried on the other hand, is a huge risk, but it may be one that National feels compelled to take. Favourites are usually favourites for a reason – but in this race, the favourites seem to have used the inside running to disqualify themselves.